SPATIAL VARIABILITY OF SOIL RESISTANCE TO PENETRATION IN NO TILLAGE SYSTEM

ABSTRACT In areas of no tillage system where there is intense traffic of machines and minimal soil mobilization, the periodic monitoring allied on localized soil compaction represent important strategies aiming agricultural sustainability. Thus, the objective of this study was to evaluate the spatial variability of soil resistance to penetration (RP) in no tillage system. Data collection took place in an experimental area of 7.65 ha using a sample grid composed of 40 points. At each point the RP was determined by three replications from which was obtained the mean RP, the maximum RP, and the depth of the maximum RP in the 0-0.40m layer. Deformed samples were randomly collected in the area to determine the water content in the soil (θ). Then the RP data were analyzed using descriptive and geostatistical statistics techniques for spatial variability maps. The RP presents spatial variability detected by means of spherical semivariogram in all soil layers. There was spatial variability in the area with the appearance of intermediate values for RP (2.00-3.00 MPa) due to no ploughing and continuous traffic of agricultural machines. There were greater reaches and critical levels of compaction on the layers 0.10-0.20 and 0.20-0.30 m where there is predominance of the maximum RP.